AIM To assess the effect of neutral(NC) and positive(PC) oral contrast use on patient dose in low-dose abdominal computed tomography(CT).METHODS Low-dose clinically indicated CTs were performed on 79 Crohn's patie...AIM To assess the effect of neutral(NC) and positive(PC) oral contrast use on patient dose in low-dose abdominal computed tomography(CT).METHODS Low-dose clinically indicated CTs were performed on 79 Crohn's patients(35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index(BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded. Data was reconstructed with pure model-based iterative reconstruction. Image quality was objectively and subjectively analysed. Data analysis was performed with Statistical Package for Social Scientists.RESULTS Higher doses were seen in neutral contrast CTs(107.60 ± 78.7 m Gy.cm, 2.47 ± 1.21 m Gy vs 85.65 ± 58.2 m Gy.cm, 2.18 ± 0.96 m Gy). The differencehad both NC and PC investigations. Image-quality assessment yielded 6952 datapoints. NC image quality was significantly superior(P < 0.001)(objective noise, objective signal to noise ratio, subjective spatial resolution, subjective contrast resolution, diagnostic acceptability) at all levels. NC bowel distension was significantly(P < 0.001) superior.CONCLUSION The use of polyethylene glycol as a neutral OC agent leads to higher radiation doses than standard positive contrast studies, in low dose abdominal CT imaging. This is possibly related to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.展开更多
Background:The effects of oral contrast agents(OCAs)on dosimetry have not been studied in detail.Therefore,this study aimed to examine the influence of OCAs on dose calculation in volumetric-modulated arc therapy plan...Background:The effects of oral contrast agents(OCAs)on dosimetry have not been studied in detail.Therefore,this study aimed to examine the influence of OCAs on dose calculation in volumetric-modulated arc therapy plans for rectal cancer.Methods:From 2008 to 2016,computed tomography(CT)images were obtained from 33 rectal cancer patients administered OCA with or without intravenous contrast agent(ICA)and 14 patients who received no contrast agent.CT numbers of organs at risk were recorded and converted to electronic densities.Volumetric-modulated arc therapy plans were designed before and after the original densities were replaced with non-enhanced densities.Doses to the planned target volume(PTV)and organs at risk were compared between the plans.Results:OCA significantly increased the mean and maximum densities of the bowels,while the effects of ICA on these parameters depended on the blood supply of the organs.With OCA,the actual doses for PTV were significantly higher than planned and doses to the bowel increased significantly although moderately.However,the increase in the volume receiving a high-range doses was substantial the absolute change of intestine volume receiving≥52 Gy:1.46[0.05-3.99,cubic centimeter range:-6.74 to 128.12],the absolute change of colon volume receiving≥50 Gy:0.34[0.01-1.53 cc,range:-0.08 to 3.80 cc].Dose changes due to ICA were insignificant.Pearson correlation showed that dose changes were significantly correlated with a high intestinal volume within or near the PTV(ρ>0.5,P<0.05)and with the density of enhanced intestine(ρ>0.3,P<0.05).Conclusions:Contrast agents applied in simulation cause underestimation of doses in actual treatment.The overdose due to ICA was slight,while that due to OCA was moderate.The bowel volume receiving≥50Gy was dramatically increased when OCA within the bowel was absent.Physicians should be aware of these issues if the original plan is barely within clinical tolerance or if a considerable volume of enhanced intestine is within or near the PTV.展开更多
Objective: To evaluate the value of oral Gd-DTPA as a negative contrast agent during magnetic resonance cholangiopancreatography (MRCP) to eliminate the high signals of the gastrointestinal tract. Methods: To select t...Objective: To evaluate the value of oral Gd-DTPA as a negative contrast agent during magnetic resonance cholangiopancreatography (MRCP) to eliminate the high signals of the gastrointestinal tract. Methods: To select the optimal concentration of oral Gd-DTPA for MRCP, a phantom study was performed followed by clinical trial in 15 cases undergoing MRCP before and after oral Gd-DTPA (in a total volume of 250 ml 1∶5 diluted Gd-DTPA, 1.488 g/L). MRCP images were acquired using two-dimensional single slice fast spin-echo (SSTSE) sequence and half-Fourier acquisition single slice fast spin-echo (HASTE) sequence. Results: The phantom study showed that the 1∶5 diluted oral Gd-DTPA was best in decreasing the signal intensity both in T2-weighted imaging (59.5%) and in HASTE sequence (82.45%). The high signal intensity of the stomach and intestinal fluid was completely suppressed in all the cases. The depictions of the common bile duct and pancreatic duct were markedly improved by using the oral contrast agent (P<0.05). Conclusion: Oral Gd-DTPA is effective and safe for eliminating the high signal of the gastrointestinal tract to improve the depiction of the biliary system by MRCP.展开更多
BACKGROUND Due to a thicker abdominal wall in some patients,ultrasound artifacts from gastrointestinal gas and surrounding tissues can interfere with routine ultrasound examination,precluding its ability to display or...BACKGROUND Due to a thicker abdominal wall in some patients,ultrasound artifacts from gastrointestinal gas and surrounding tissues can interfere with routine ultrasound examination,precluding its ability to display or clearly show the structure of a hernial sac(HS)and thereby diminishing diagnostic performance for esophageal hiatal hernia(EHH).Contrast-enhanced ultrasound(CEUS)imaging using an oral agent mixture allows for clear and intuitive identification of an EHH sac and dynamic observation of esophageal reflux.CASE SUMMARY In this case series,we report three patients with clinically-suspected EHH,including two females and one male with an average age of 67.3±16.4 years.CEUS was administered with an oral agent mixture(microbubble-based SonoVue and gastrointestinal contrast agent)and identified a direct sign of supradiaphragmatic HS(containing the hyperechoic agent)and indirect signs[e.g.,widening of esophageal hiatus,hyperechoic mixture agent continuously or intermittently reflux flowing back and forth from the stomach into the supradiaphragmatic HS,and esophagus-gastric echo ring(i.e.,the“EG”ring)seen above the diaphragm].All three cases received a definitive diagnosis of EHH by esophageal manometry and gastroscopy.Two lesions resolved upon drug treatment and one required surgery.The recurrence rate in follow-up was 0%.The data from these cases suggest that the new non-invasive examination method may greatly improve the diagnosis of EHH.CONCLUSION CEUS with the oral agent mixture can facilitate clear and intuitive identification of HS and dynamic observation of esophageal reflux.展开更多
This study aimed to investigate the protective effect of oral steroid premedication in terms of adverse reactions to non-ionic contrast media. We investigated the incidence of adverse reactions among patients who unde...This study aimed to investigate the protective effect of oral steroid premedication in terms of adverse reactions to non-ionic contrast media. We investigated the incidence of adverse reactions among patients who underwent contrast-enhanced computed tomography. Patients in the premedication group took 30 mg of prednisolone orally the night before and on the morning of the scheduled computed tomography. Sixty-five patients received the same contrast media. Among them, 56 took prednisolone orally prior to the procedure (premedication without change of contrast media group) and nine without premedication (no premedication and no change of contrast media group). In total, 379 patients received different contrast media. Among them, 340 took prednisolone orally (premedication with change of contrast media group), while 39 did not take the premedication (no premedication with change of contrast media group). The adverse reaction rates in the premedication with change of contrast media and no premedication with change of contrast media groups were 1.8% (6/340 cases) and 2.6% (1/39 cases) (P = 0.54), respectively. The incidence of adverse reaction after the administration of non-ionic iodinated contrast media did not differ significantly based on whether an oral steroid was administered prior to compute tomography. Our evaluation is limited due to the small sample size of the contrast media-changed group. However, even if premedication with steroids is effective, it may only result in an adverse reaction reduction rate of ≤3%.展开更多
After Institutional Review Board approval, 109 patients ≥ 18 years old undergoing intravenously enhanced Computed Tomography (CT) of the abdomen and pelvis were prospectively enrolled and randomized into two arms. Pa...After Institutional Review Board approval, 109 patients ≥ 18 years old undergoing intravenously enhanced Computed Tomography (CT) of the abdomen and pelvis were prospectively enrolled and randomized into two arms. Patients with a history of inflammatory bowel disease, Crohn disease and ulcerative colitis were excluded. The control arm received routine enteric contrast and intravenous contrast. The experimental arm did not receive oral contrast, but received the standard dose of intravenous (IV) contrast. One of four experienced body radiologists reviewed the studies and rated his/her confidence on a scale of 1 (no confidence) to 10 (all confident findings have been made). Confidence levels were compared between groups. The 109 subjects were distributed 54 (49.5%) in the control arm and 55 (50.5%) in the experimental arm. The average confidence level in the control arm was 8.7 ± 0.9 versus 8.4 ± 1.1 in the experimental arm, which is not statistically significant (p value = 0.09). Among radiologists, the average confidence levels ranged from 6 - 10 in the control arm and 7 - 10 in the experimental arm. No examinations were repeated for technical considerations in either group. No studies were repeated in the experimental group in order to administer oral contrast. When each radiologist was compared to the others, there were no differences in confidence level between pairs in the control arm;however, there were statistically significant differences in confidence level among three pairs of radiologists for the experimental arm. There was no statistically significant difference in radiologist confidence level between intravenously enhanced abdomen and pelvis CTs with enteric contrast and without enteric contrast.展开更多
文摘AIM To assess the effect of neutral(NC) and positive(PC) oral contrast use on patient dose in low-dose abdominal computed tomography(CT).METHODS Low-dose clinically indicated CTs were performed on 79 Crohn's patients(35 = PC, 1 L 2% gastrografin; 44 = NC, 1.5 L polyethylene glycol). Scanner settings for both acquisitions were identical apart from 25 s difference in intravenous contrast timing. Body mass index(BMI), scan-ranges, dose-length product and size-specific dose estimated were recorded. Data was reconstructed with pure model-based iterative reconstruction. Image quality was objectively and subjectively analysed. Data analysis was performed with Statistical Package for Social Scientists.RESULTS Higher doses were seen in neutral contrast CTs(107.60 ± 78.7 m Gy.cm, 2.47 ± 1.21 m Gy vs 85.65 ± 58.2 m Gy.cm, 2.18 ± 0.96 m Gy). The differencehad both NC and PC investigations. Image-quality assessment yielded 6952 datapoints. NC image quality was significantly superior(P < 0.001)(objective noise, objective signal to noise ratio, subjective spatial resolution, subjective contrast resolution, diagnostic acceptability) at all levels. NC bowel distension was significantly(P < 0.001) superior.CONCLUSION The use of polyethylene glycol as a neutral OC agent leads to higher radiation doses than standard positive contrast studies, in low dose abdominal CT imaging. This is possibly related to the osmotic effect of the agent resulting in larger intraluminal fluid volumes and resultant increased overall beam attenuation.
基金This work was supported by the grants from the National Key Projects of Research and Development of China(No.2016YFC0904600)the Beijing Municipal Science&Technology Commission of China(No.Z171100001017116)。
文摘Background:The effects of oral contrast agents(OCAs)on dosimetry have not been studied in detail.Therefore,this study aimed to examine the influence of OCAs on dose calculation in volumetric-modulated arc therapy plans for rectal cancer.Methods:From 2008 to 2016,computed tomography(CT)images were obtained from 33 rectal cancer patients administered OCA with or without intravenous contrast agent(ICA)and 14 patients who received no contrast agent.CT numbers of organs at risk were recorded and converted to electronic densities.Volumetric-modulated arc therapy plans were designed before and after the original densities were replaced with non-enhanced densities.Doses to the planned target volume(PTV)and organs at risk were compared between the plans.Results:OCA significantly increased the mean and maximum densities of the bowels,while the effects of ICA on these parameters depended on the blood supply of the organs.With OCA,the actual doses for PTV were significantly higher than planned and doses to the bowel increased significantly although moderately.However,the increase in the volume receiving a high-range doses was substantial the absolute change of intestine volume receiving≥52 Gy:1.46[0.05-3.99,cubic centimeter range:-6.74 to 128.12],the absolute change of colon volume receiving≥50 Gy:0.34[0.01-1.53 cc,range:-0.08 to 3.80 cc].Dose changes due to ICA were insignificant.Pearson correlation showed that dose changes were significantly correlated with a high intestinal volume within or near the PTV(ρ>0.5,P<0.05)and with the density of enhanced intestine(ρ>0.3,P<0.05).Conclusions:Contrast agents applied in simulation cause underestimation of doses in actual treatment.The overdose due to ICA was slight,while that due to OCA was moderate.The bowel volume receiving≥50Gy was dramatically increased when OCA within the bowel was absent.Physicians should be aware of these issues if the original plan is barely within clinical tolerance or if a considerable volume of enhanced intestine is within or near the PTV.
文摘Objective: To evaluate the value of oral Gd-DTPA as a negative contrast agent during magnetic resonance cholangiopancreatography (MRCP) to eliminate the high signals of the gastrointestinal tract. Methods: To select the optimal concentration of oral Gd-DTPA for MRCP, a phantom study was performed followed by clinical trial in 15 cases undergoing MRCP before and after oral Gd-DTPA (in a total volume of 250 ml 1∶5 diluted Gd-DTPA, 1.488 g/L). MRCP images were acquired using two-dimensional single slice fast spin-echo (SSTSE) sequence and half-Fourier acquisition single slice fast spin-echo (HASTE) sequence. Results: The phantom study showed that the 1∶5 diluted oral Gd-DTPA was best in decreasing the signal intensity both in T2-weighted imaging (59.5%) and in HASTE sequence (82.45%). The high signal intensity of the stomach and intestinal fluid was completely suppressed in all the cases. The depictions of the common bile duct and pancreatic duct were markedly improved by using the oral contrast agent (P<0.05). Conclusion: Oral Gd-DTPA is effective and safe for eliminating the high signal of the gastrointestinal tract to improve the depiction of the biliary system by MRCP.
基金The Research Project of Sichuan Medical Association,Nos.S19080 and S18075.
文摘BACKGROUND Due to a thicker abdominal wall in some patients,ultrasound artifacts from gastrointestinal gas and surrounding tissues can interfere with routine ultrasound examination,precluding its ability to display or clearly show the structure of a hernial sac(HS)and thereby diminishing diagnostic performance for esophageal hiatal hernia(EHH).Contrast-enhanced ultrasound(CEUS)imaging using an oral agent mixture allows for clear and intuitive identification of an EHH sac and dynamic observation of esophageal reflux.CASE SUMMARY In this case series,we report three patients with clinically-suspected EHH,including two females and one male with an average age of 67.3±16.4 years.CEUS was administered with an oral agent mixture(microbubble-based SonoVue and gastrointestinal contrast agent)and identified a direct sign of supradiaphragmatic HS(containing the hyperechoic agent)and indirect signs[e.g.,widening of esophageal hiatus,hyperechoic mixture agent continuously or intermittently reflux flowing back and forth from the stomach into the supradiaphragmatic HS,and esophagus-gastric echo ring(i.e.,the“EG”ring)seen above the diaphragm].All three cases received a definitive diagnosis of EHH by esophageal manometry and gastroscopy.Two lesions resolved upon drug treatment and one required surgery.The recurrence rate in follow-up was 0%.The data from these cases suggest that the new non-invasive examination method may greatly improve the diagnosis of EHH.CONCLUSION CEUS with the oral agent mixture can facilitate clear and intuitive identification of HS and dynamic observation of esophageal reflux.
文摘This study aimed to investigate the protective effect of oral steroid premedication in terms of adverse reactions to non-ionic contrast media. We investigated the incidence of adverse reactions among patients who underwent contrast-enhanced computed tomography. Patients in the premedication group took 30 mg of prednisolone orally the night before and on the morning of the scheduled computed tomography. Sixty-five patients received the same contrast media. Among them, 56 took prednisolone orally prior to the procedure (premedication without change of contrast media group) and nine without premedication (no premedication and no change of contrast media group). In total, 379 patients received different contrast media. Among them, 340 took prednisolone orally (premedication with change of contrast media group), while 39 did not take the premedication (no premedication with change of contrast media group). The adverse reaction rates in the premedication with change of contrast media and no premedication with change of contrast media groups were 1.8% (6/340 cases) and 2.6% (1/39 cases) (P = 0.54), respectively. The incidence of adverse reaction after the administration of non-ionic iodinated contrast media did not differ significantly based on whether an oral steroid was administered prior to compute tomography. Our evaluation is limited due to the small sample size of the contrast media-changed group. However, even if premedication with steroids is effective, it may only result in an adverse reaction reduction rate of ≤3%.
文摘After Institutional Review Board approval, 109 patients ≥ 18 years old undergoing intravenously enhanced Computed Tomography (CT) of the abdomen and pelvis were prospectively enrolled and randomized into two arms. Patients with a history of inflammatory bowel disease, Crohn disease and ulcerative colitis were excluded. The control arm received routine enteric contrast and intravenous contrast. The experimental arm did not receive oral contrast, but received the standard dose of intravenous (IV) contrast. One of four experienced body radiologists reviewed the studies and rated his/her confidence on a scale of 1 (no confidence) to 10 (all confident findings have been made). Confidence levels were compared between groups. The 109 subjects were distributed 54 (49.5%) in the control arm and 55 (50.5%) in the experimental arm. The average confidence level in the control arm was 8.7 ± 0.9 versus 8.4 ± 1.1 in the experimental arm, which is not statistically significant (p value = 0.09). Among radiologists, the average confidence levels ranged from 6 - 10 in the control arm and 7 - 10 in the experimental arm. No examinations were repeated for technical considerations in either group. No studies were repeated in the experimental group in order to administer oral contrast. When each radiologist was compared to the others, there were no differences in confidence level between pairs in the control arm;however, there were statistically significant differences in confidence level among three pairs of radiologists for the experimental arm. There was no statistically significant difference in radiologist confidence level between intravenously enhanced abdomen and pelvis CTs with enteric contrast and without enteric contrast.
